Let’s come directly in the topic. The most important books that you must read or go through for HISTORY if you want to clear UPSC Prelims and Mains.

For Prelims :-

1. RS Sharma or Tamil Nadu Board Book for Ancient India
2. Class 7 ( Old NCERT ) or Satish Chandra for Medieval India
3. Spectrum for Modern India + Shekhar Bandopadhyay ( Glossary and definitions)
4. Class XI Fine Arts NCERT for Art and Culture

For MAINS:-

For Mains some new things are added like the World History :

So For World History : Class IX, X Old NCERT ( ARJUN DEV )

Also Read Shekhar Bandopadhyay in totality for the Mains as well.

For World History one can also refer to the Sriram IAS Notes available in the market.